A fuel cell is a device that generates electrical power by the electrochemical reaction of fuel gas, such as hydrogen, and air (oxygen), and has high power generation efficiency because of the capacity to directly convert chemical energy to electricity. In particular, a solid oxide fuel cell (hereinafter referred to as SOFC) having an operation temperature of 1000° C. or lower has bright prospects due to its high reaction rate. In a SOFC, a membrane electrode assembly (MEA) in which an electrolyte layer containing a solid oxide and two electrodes formed of ceramic (sintered bodies) sandwiching the electrolyte layer are integrated is used. In other words, handling is easy since all of the constitutional elements of the MEA are solid.
Typically, in order to obtain high power, multiple MEAs are stacked and arranged. An interconnector (separator) that separates fuel gas and air from each other is disposed between the MEAs. The interconnector also has a current collecting function for extracting the generated power to the exterior.
A fuel cell needs gas channels adjacent to the MEAs in order to supply fuel gas or air to the MEAs. In order to obtain gas channels, for example, in PTL 1, an expand metal is disposed between a MEA and an interconnector. PTL 2 teaches a method for forming dimples, which serve as gas channels, in the interconnector by etching or the like.